Needle jogging mechanisms for sewing machines



y 3, 1969 a. D. WULBREDE m 3,443,538 I l I NEEDLE JOGGING MECHANISMS FOR SEWING MACHINES v Filed June 15, 1967 Sheet of 4 INVENTORS Ernst D. Wulbrede I? v Erich M. Willenbacher WITNESS Dieter K. Gab/er BY ,yT TORNEY May 1969 E. D. WULBREDE ET AL 3,443,538

- NEEDLE JOGGING MECHANISMS FORSEWING MACHINES Filed June 13. 1967 Sheet 2 INVENTORS 'ifi-vvfl i h nc I an ac er WITNESS Dieter K. Gab/er NEEDLE, JOGGINC' MECHANISMS FOR SEWING MACHINES Filed June 15, 1967 Sheet 3 of 4" Fig.3

INVENTORS Ernst D. Wulbrede Dieter K. Gab/er WIT/V5155 3 Ench M. WIHQflbOChQIfV ATTORNEY May 13, 1969 WULBREDE ET AL I 3,443,538

NEEDLE JOGGING MECHANISMS FOR SEWING MACHINES Filed June 13,,1967 Sheet 4 of 4 RS ede Ilenbacher Gabler I-NVENTO ujbr WI yA TTORNEY Ernst D. W Erjch M. Dlefer K.

Fig.4

WITNESS United States Patent O 3,443,538 NEEDLE JOGGING MECHANISMS FOR SEWING MACHINES Ernst Diekiele Wulbrede and Erich M. Willenbacher, Karlsruhe-Hagsfeld, and Dieter K. Gabler, N eudorf, Germany, assignors to The Singer Company, New York,

N.Y., a corporation of New Jersey Filed June 13, 1967, Ser. No. 645,803 Int. Cl. Db 3/02 US. Cl. 112-158 5 Claims ABSTRACT OF THE DISCLOSURE A bracket having a slideway which embraces a bearing concentric with a cam, and cam followers at each end of the bracket contacting a cam surface of the cam to impart lateral oscillation to a needle bar gate in a sewing machine without floating away of the cam followers from the cam surface of the cam.

BACKGROUND OF THE INVENTION Field of the invention The invention relates to needle jogging mechanisms for sewing machines.

Description of the prior art Basically, in a zigzag sewing machine, a needle bar is mounted on a needle bar gate. The needle bar gate is mounted in the frame of the sewing machine for lateral oscillation. Lateral oscillation is imparted to the needle bar gate by a cam and cam follower, and transmitted to the needle bar gate by a connecting rod between the cam follower and the needle bar gate. The cam follower is biased against the cam surface of the cam by a spring. Because of the high operating speeds of modern sewing machines, there is a tendency for the cam follower to float away from the cam surface of the cam at certain speeds. The floating away of the cam follower from the cam surface of the cam causes nonuniform stitch patterns since full lateral oscillation is not imparted to the needle gate for every stitch.

SUMMARY OF THE A INVENTION It is, therefore, an object of the invention to provide an improved needle jogging mechanism for a sewing machine.

Another =object of the invention is to provide a needle jogging mechanism for a sewing machine having a cam and a cam follower for imparting lateral oscillation to a needle bar gate in which the cam follower cannot float away from the cam surface of the cam thus producing stitch patterns which are more uniform than those produced by present sewing machines.

Other objects and a fuller understanding of the invention may be had by referring to the description and claims taken in conjunction with the accompanying drawmgs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a rear elevational view partly in section of a sewing machine showing a first modification of the invention,

FIG. 2 is an enlarged cross sectional view taken substantially along the line 22 in FIG. 1.

FIG. 3 is a rear elevational view partly in section of a sewing machine showing a second modification of the invention.

FIG. 4 is an enlarged detail view taken substantially along the line 4-4 in FIG. 3, and

3,443,538 Patented May 13, 1969 FIG. 5 is an enlarged cross sectional view taken substantially along the line 55 in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawings, a first modification of the invention is illustrated in FIGS. 1 and 2. The first modification of the invention is illustrated as embodied in a sewing machine having a frame including a work-supportmg bed 11, a hollow standard 12 rising from one of the bed, a hollow bracket arm 13 at the top of the standard overhanging the bed, and a hollow sewing head 14 at the free end of the bracket arm.

Mounted in the sewing head is a needle bar gate 15. The needle bar gate is connected to the end of a slide rod 16 which is mounted in bearings 17 in the bracket arm for lateral oscillation of the needle bar gate. A pair of guide pins 18, of which only one is shown, embrace the side of the needle bar gate permitting lateral oscillation but preventing rotation.

Mounted on the needle bar gate for axial reciprocation is a needle bar 19. A needle 20 is removably connected to the end of the needle bar. Axial reciprocation is imparted to the needle bar through a conventional crank mechanism indicated generally at 21. The crank mechanism includes a crank 22 which is locked to the end of an arm shaft 23 by a roll pin 24. The crank has a crankpin 25 and the needle bar has a clamp 26 which carries a pivot pin 27. A link 28 is pivotally mounted on the crankpin of the crank and the pivot pin 27 of the needle bar to transmit axial reciprocation to the needle bar. The arm shaft is journaled in bearings 28 in the bracket arm and is rotated through a pulley 30 on a handwheel 31 at the standard end of the arm shaft by a conventional V-belt connected to a motor or foot treadle which are not shown.

Also journaled in the bracket arm in bearings 32 is a cam shaft 33. The cam shaft is rotated through a Worm 34 on the arm shaft which meshes with a worm wheel 35 on the cam shaft. The Worm and the worm wheel are locked to the arm and cam shafts, respectively, by setscrews 36 and 37.

Also mounted on the cam shaft is a hub 38 which is locked to the cam shaft by a setscrew 39. A cam 40 is mounted on the hub and locked to the hub by screws 41 which extend through clearance holes 42 in a flange 43 on the hub, through clearance holes 44 in the cam, and into tapped holes 45 in a disk 46 which is also mounted on the hub. The cam has a cam surface 47 which generates three stitches during each zigzag crossing or six stitches in each zigzag cycle. Therefore, the ratio of teeth on the worm and the worm wheel are such that the arm shaft rotates six times to produce six needle penetrations for each rotation of the cam shaft. The cam may be composed of nylon.

In addition to the worm wheel and the hub for the cam, a bearing 48 having parallel bearing surfaces 49 is mounted on the cam shaft. A slideway 50 in a bracket 51 slides on the bearing surfaces of the bearing. Two cam follower rollers 52 and 53 having roller bearings 54 and 55 are journaled on pins 56 and 57 at the ends of the bracket 51 and contact the cam surface of the cam.

An arm 58 having an car 59 is pivotally connected to the pin 57 for the uppermost cam follower roller 53 with the cam follower roller housed between the arm 58 and the car 59. Suitable spacers 60 and 61 are provided on, the pins 56 and 57 to position the cam follower rollers in tandem alignment with the cam. One end of the arm 58 is connected to a pivot pin 62 held between a pair of ears 63 on a clamp 64 on the slide rod 16. The other end of the arm is pivotally connected to a collar 65 which slides on a slideway in the form of a pin 66 held by a frame 67. The frame is adjustable to change the angular and lateral orientations of the pin 66 as described in a copending United States patent application Ser. No. 363,890 of Ernst Wulbrede and Gerhard Sewing, filed Apr. 30, 1964, and now Patent No. 3,313,258.

A second modification of the invention is illustrated in FIGS. 3 to 5. The second modification of the invention is illustrated as embodied in the same sewing machine as the first modification and employs many of the same parts. Only the differences of the second modification over the first modification will be described. It is understood that the remaining parts of the second modification are substantially the same as those in the first modification and in fact are identified with the same reference numerals but sufiixed with a letter a to distinguish from those in the first modification.

Turning now to the second modification of the invention, a cam 68 is provided having a cam surface 69 which generates two stitches during each zigzag crossing or four stitches in each zigzag cycle. Since there are three zigzag cycles on the cam surface of the cam, the ratio of teeth on a worm 70 on the arm shaft and a worm wheel 71 on the cam shaft are such that the arm shaft rotates twelve times to produce twelve needle penetrations for each rotation of the cam shaft. As in the first modification, the cam may be composed of nylon.

Contrary to the first modification of the invention, a bearing 72 is provided which is not free to pivot on the cam shaft, but instead is locked in a position with parallel bearing surfaces 73 oriented in a vertical position. The bearing 72 is locked in a vertical position by a pair of screws 74 which extend through clearance holes 75 in the bracket arm and into tapped holes 76 in the bearing. The bearing 72 also serves as one of the bearings for the cam shaft. Since the bearing is not free to pivot on the cam shaft, to prevent binding, a link 77 must be provided between the bracket and a modified arm 78 having an car 79. The link 77 is pivotally connected to the pin 57a for the uppermost cam follower roller 53a and to a pin 80 held between the arm 78 and the ear 79.

In operation, in the modification of FIGS. 1 and 2, rotation of the cam 40 causes the cam follower rollers 52 and 53 to move the bracket 51 pivotally and up and down on the bearing 48 thus moving the arm 58 so that lateral oscillation is imparted to the slide rod 16 and hence to the needle bar gate 15. As described in the foregoing United States patent application Ser. No. 363,890, the angular orientation of the pin 66 determines the width of the stitches and the lateral position of the pin 66 determines the center position of the needle. Since the axes of the cam follower rollers 52 and 53 are always in line with the axis of the cam 40, the cam follower rollers are always in contact with the cam surface 47 of the cam and hence cannot float away from the cam surface of the cam.

The operation of the modification of FIGS. 3 to 5 is substantially the same as the operation of the modification of FIGS. 1 and 2 except that, in the modification of FIGS. 3 to 5, since the bearing 72 is always located in a vertical position, the link 77 must be provided to prevent binding. The modification of FIGS. 3 to 5 eliminates the variable caused by pivotal movement of the bearing 72.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention.

Having thus set forth the nature of the invention, what is claimed is:

1. A needle jogging mechanism for a sewing machine having a frame, a needle bar gate, means for mounting the needle bar gate in the frame for lateral oscillation, a needle bar for a needle, means for mounting the needle bar on the needle bar gate for axial reciprocation, and means for imparting axial reciprocation to the needle bar, said needle jogging mechanism comprising a cam having a cam surface, means for mounting the cam in the frame for rotation, means for imparting rotation to the cam, a bearing, means for mounting the bearing in the frame substantially concentric with the cam, a bracket having a slideway which embraces the bearing, a cam follower at each end of the bracket contacting the cam surface of the cam, and means connected to the bracket for transmitting lateral oscillation to the needle bar gate.

2. The needle jogging mechanism of claim 1 in which the means for mounting the cam and the bearing is a cam shaft and the bearing has parallel bearing surfaces substantially equidistant from the axis of the cam shaft and contacting the sides of the slideway.

3. The needle jogging mechanism of claim 2 in which the cam followers are cam follower rollers.

4. The needle jogging mechanism of claim 3 in which the means for transmitting lateral oscillation to the needle bar gate is an arm and which includes a second slideway mounted in the frame, means for pivotally connecting the arm to the bracket, means for pivotally connecting the arm to the needle bar gate, and means for pivotally and slidably connecting the arm to the second slideway.

5. The needle jogging mechanism of claim 4 which includes means for locking the bearing against pivotal movement, a link interposed between the bracket and the arm, means for pivotally connecting the link to the bracket, and means for pivotally connecting the link to the arm.

References Cited UNITED STATES PATENTS RICHARD J. SCANLAN, JR., Primary Examiner. 

